This invention relates to flame retardant polyamide compositions having improved arc tracking resistance.
Flame retardant polyamide molding compositions are used extensively for the manufacture of articles and parts for electrical applications. For such purposes it is often required that the polyamide composition exhibit a high arc tracking resistance as well as flame retardant properties.
U.S. Pat. No. 4,247,450 discloses polyamide compositions having both fire resistance and arcing resistance, comprising a polyamide, 5 to 25 percent of a flameproofing agent, 0.2 to 20 percent cadmium oxide and, optionally, an additional inorganic compound such as zinc borate. The flame proofing agent may be a reaction product of two moles of hexachlorocylopentadiene and one mole of cyclooctadiene.
U.S. Pat. No. 4,105,621 to Maslen et al discloses flame retardant polyamide compositions having arc tracking resistance comprising 30-74.95 percent polyamide, 15-55 percent glass fiber, 5-30 percent of a halogenated flame retardant, 5-30 percent zinc borate, 0.05 to 15 percent of an oxide such as antimony oxide or zinc oxide. The preferred halogenated fire retardants are compounds described in British Patent Specification No. 1,090,598, especially the compound of the formula C.sub.18 H.sub.12 Cl.sub.12 (corresponding to structural formula (I), below).
U.S. Pat. No. 4,360,616 to Pagiligan discloses flame retardant polyamide compositions having arc tracking resistance, comprising (a) 40-65 weight percent polyamide, (b) 16-35 weight percent melamine, melam, melamine cyanurate, or a melamine derivative, (c) 1-7 weight percent of a chlorinated compound prepared from condensation of two moles of perchlorocyclopentadiene and one mole of 1,5-cyclooctadiene, (d) 1-4.9 weight percent of zinc borate or zinc oxide (e) 5-30 weight percent glass fibers.